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Finite-volume time-domain (FVTD) modelling of a broadband double-ridged horn antenna. (English) Zbl 1053.78011

The authors analyze the suitability of the finite-volume time-domain method (FVTD) for complex electromagnetic problems. In the FVTD algorithm presented here, tetrahedrons with a typical side length of \(\lambda/10\) are used as elementary cells in a cell-centered FVTD scheme, where both the electrical and the magnetic field components are defined at the same location in the mesh (tetrahedral barycentre). Both the electric permitivity and the magnetic permeability are assumed to be linear, homogeneous, non-dispersive and isotropic in each cell. Second-order accuracy in space is achieved by using estimated gradients in the cell barycentres to compute the fields at the face centres according to the monotonic upwind scheme for conservation laws, whereas second-order accuracy in time is attained applying the Lax-Wendroff predictor-corrector scheme. To limit the computational area a Silver-Müller RBC is implemented. To avoid reflection the outgoing waves have to impinge perpendicularly onto the boundary. Energy needed to excite a structure is coupled into the system through either point sources or constrained fields. To perform a full-wave S-parameters extraction, a port plane (similar to a source plane) is embedded in the mesh. To compute the far-field radiation pattern, Love’s equivalent principle is used. FVTD scheme needs ten times larger memory per cell in comparison to classical finite-difference time-domain scheme (FDTD). However, authors claim that significant saving of resources can be achieved respect to FDTD in the inhomogeneous meshes. A broadband double-ridged horn antenna is simulated with this FVTD code. The horn antenna consists of non-orthogonal and curved parts and a small coaxial feeding that is modelled in detail. Curved and oblique surfaces as well as fine structural details are treated accurately since the core FVTD algorithm works in a unstructured tetrahedral mesh, unaffected by the cells shape and size. In a single simulation run, the near field data, the radiation patterns and the scattering parameters of the antenna have been calculated for a frequency range of 1-18 GHz. A good agreement was found with the measurement data.

MSC:

78A50 Antennas, waveguides in optics and electromagnetic theory
35Q60 PDEs in connection with optics and electromagnetic theory
78M25 Numerical methods in optics (MSC2010)
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